"By around 5:15 a.m. and 5:17 a.m. Line 1 and Line 2 were tried, but they all tripped immediately on the same relay indication," the TCN said.
The Transmission Company of Nigeria (TCN) on Tuesday said its 330kV Ugwaji-Apir Double Circuit transmission lines 1 & 2 tripped due to a fault, resulting in a forced power outage affecting the communities in the North-east, North-west and parts of North-central.
The TCN General Manager Public Affairs, Ndidi Mbah, made this known in a statement on Tuesday.
Ms Mbah said at approximately 4:53 a.m. on Monday, the Ugwuaji-Markurdi 330kV Line 2 tripped and 243 MW on that line was transferred to Line 1 on the same route.
She explained that at 4:58 a.m., Line 1 also tripped, resulting in a total loss of 468 MW.
"By around 5:15 a.m. and 5:17 a.m. Line 1 and Line 2 were tried, but they all tripped immediately on the same relay indication.
"Following the tripping incidents yesterday, two teams of linesmen were dispatched. One from the Apir Transmission Sub-region and another from the Enugu transmission to expedite fault tracing along the 215 km route, which includes 245 transmission towers," she said.
She noted that throughout Monday, the Apir team patrolled the line, navigating challenging terrains in search of the fault, reaching as far as the River Benue.
"They were unable to locate the cause of the tripping and have continued in the fault tracing early this morning."
Meanwhile, she said the lines patrol team from the Enugu Region of TCN were unable to commence lines patrol on Monday due to the 'sit-at-home' directive in the South-east for 21 and 22 October.
This, she said, hindered not only the patrol team but also made it difficult to refuel patrol vehicles for the long-distance line trace.
"Arrangements were, however, made for security operatives to guide the team, who have commenced fault tracing this morning," she added.
She said the TCN has restored supply to the 132kV transmission line from New Haven to Apir, but the 330kV lines remain out of service, impacting power supply in large parts of the Northern region of the country.
Sadly, she said, the TCN Shiroro-Mando transmission line is also down due to security reasons, causing a power outage in the North.
"TCN is making every effort to trace the cause of the outage to enable our engineers to effect repairs and restore bulk power supply through both lines.
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"We sincerely apologise to the government and electricity consumers in all the affected states and acknowledge that our patrol teams would have continued their search into the night yesterday, if not for the challenging terrain, which includes swamps and rivers, as well as insecure areas in the forest.
"We reconvened very early this morning with security operatives and have continued the fault tracing to locate and address the cause of the line tripping," she said.
In recent years, the power sector has experienced many challenges in areas of electricity policy enforcement, regulatory uncertainty, gas supply, transmission system constraints, and significant power sector planning shortfalls.
In November 2013, the federal government privatised all power generation and 11 distribution companies, with the government retaining the ownership of the transmission company. This was to improve efficiency in the sector.
However, since the privatisation, the grid has continued to collapse amid efforts to reposition the power sector.
On Monday, the Nigerian Electricity Regulatory Commission (NERC) said it will conduct an investigative public hearing on 24 October to address the recurring grid collapses and widespread outages.
